Perfluoro-substituted aliphatic acids and derivatives thereof



ni ted States PERFLUORO-SUBSTITUTED ALIPHATIC ACIDS AND DERIVATIVESTHEREOF No Drawing. Filed June 26, 1957, Ser. No. 668,027

23 Claims. (Cl. 260-23) This invention relates to terminallyperfluoroalkylated aliphatic carboxylic acids and to derivativesthereof.

Perfluoroaliphatic carboxylic acids and acids of similar type in whichthere is interposition of a methylene group between the carboxyl andperfiuoroalkyl groups are known. The latter may conveniently bedesignated as 2,2-dihydroperfiuoroalkyl carboxylic acids. These knowncompounds are strong acids containing over 50% combined fluorine inwhich the strength of the ordinary carboxyl group is enhanced by theproximity of the highly fluorinated alkyl groups. Fluorinated acids andderivatives thereof have desirable oleophobic and hydrophobicproperties; but the strongly acid nature of the known compoundsintroduces certain disadvantages. For example, the perfiuoro carboxylicacids approach the acidity of mineral acids and are highly corrosive anddangerous to handle. Their derivatives are relatively easily hydrolyzedand the metallic salt complexes of these strong acids tend to be labile.The 2,2-dihydroperfluoro-carboxylic acids are unstable in alkalinemedia.

It is an object of this invention to provide stable acids andderivatives thereof possessing the desirable oleophobic and hydrophobicproperties of perfluoroalkyl groups, but in which the ordinarily strongacidity of such perfiuorL nated carboxylic acids has been moderated. Itis a further object of the invention to provide polymerizablederivatives of such acids. Still further objects of the invention willbe apparent from the following disclosure.

In accordance with the above and other objects of the invention, it hasbeen found that acids represented by the general formula:

wherein R is a monovalent, functionally unsubstituted perfluorinatedgroup having from 4 to 12 carbon atoms and includes perfluorinated alkyland cycloalkyl radicals, and R is a straightchain alkylene group havingfrom 1 to 12 carbon atoms, have low acid strength while unexpectedlyretaining the desirable oleophobic properties of the perfluorinatedgroup.

As illustrative examples of acids coming within the scope of the presentinvention there may be mentioned: 5-perfluorobutylpentanoic acid,7-perfiuoroamylheptanoic acid, 6-perfluorododecylhexanoic acid,omega-perfluorobutyl-myristic acid, 9-perfluorooctyl-nonanoic acid, 5-perfluorooctylpentanoic acid, ll-perfluorooctyl-hendecanoic acid,l2-perfluorooctyl-dodecanoic acid, and 8- perfluorocyclohexyl octanoicacid.

The presence of the chain of 3 or more carbon atoms between the R group,as defined above, and the carboxyl group, renders these acids lessstrongly acid than the perfluorinated acids lacking this alkylene chainby as much as 1000 fold or more. For certain purposes this markedlylowered acidity is highly desirable. It results in greatly increasedresistance of the esters of the acids of the invention to hydrolysis inneutral and basic media. It promotes increased stability of the metallicsalt-complexes, such as for example the chromium complex, and it greatlyreduces the corrosiveness of the free acidsv and of the amine orammonium salts toward electropositive 2,951,051 Patented Aug. 30,1960

ice

metals and toward skin tissues. Surprisingly, at the same time the acidsof the invention and their derivatives retain the desirable oleophobicproperties conferred by the R group and, when the alkylene group R is inthe range of l to 12 carbon atoms, the soluble salts of these acids havea balance of fiuophilic, oleophobic and hydrophilic propertiespossessing particular value as emulsifying agents for use in thepolymerization of monomers of the fluorocarbon type. The term fiuophilicis here coined to describe the novel property of afiinity forfluorocarbon-type materials, and includes both solubility andwettability phenomena involving such materials. For xarnple, the vinyland allyl esters of the chlorinated precursor intermediates of the acidsof the present invention, of the type R -CH CHCl(CH CH CO H wherein n is0 to 11, as well as the vinyl and allyl esters of the acids of theinvention themselves, can be emulsionpolymerized in the presence ofsalts of these latter acids as emulsifying agents.

Included within the scope of the invention are the simple derivatives ofthe described perfluoroalkylated aliphatic acids. It is convenient todesignate these derivatives of the acids of the invention by the termcarboxyllinked derivatives. This term as used herein signifiesderivatives formed both by replacement of the hydrogen ion of thecarboxyl group by another cation, as in the salts and complexes, andderivatives formed by formal dehydration reactions as for example acylhalides, anhydrides, amides, amidines, nitriles, hydrazides, peroxides,esters, orthoesters and the like.

Broadly speaking, the acids of the invention can be produced bysuccessively dehydrohalogenating penultimately chlorinated acids formed,for example, by desulfonylative addition ofa perfluorinated sulfonylchloride to a terminally unsaturated aliphatic carboxylic acid andreducing the resultant fiuorinated unsaturated acids, for example, byhydrogenation. Intermediate terminally'unsaturated acids having thedesired carbon chain lengths for preparation of the compounds of theinvention can be prepared by hydrolysis of the alkenylmalonic estersproduced by the repeated use of the malonic ester synthesis, describedin the textbook of R. B. Wagner and H. D. Zook, entitled SyntheticOrganic Chemistry, pages 427-428, John Wiley and Sons, Inc., New York,1953.

The following series of equations, in which R, has the same significanceas hereinabove, illustrates the preparation of an w-perfluoroalkylhendecanoic acid.

Alternatively, the compounds of the invention areconveniently anddirectly prepared by catalytic protodechlorination (reductivedehydrohalogenation) of the halogenated acids produced as set forthabove.

Still another method by which the acids of this invention can beproduced is by addition of a perfluoroalkyl iodide to an unsaturatedaliphatic acid, followed by catalytic protodeiodination, as illustratedby the equation:

catalytic protodeiodination salt.

wherein R; again has the significance described hereinabove. By thecatalytic protodehalogenation processes the reduced acids are formedwithout the necessity for intermediate isolation of unsaturated acids.While it is possible that the reactions described proceed step-wise sothat fluorocarbon-substituted unsaturated acids are first formed in thereaction mixture and then are reduced, whereby unsaturated impuritiesmight remain in the product acids if hydrogenation conditions were notvigorous enough, such impurities are readily completely reduced, whennecessary, by continued or repeated hydrogenation. Their formation isprecluded when the hydrogenation step is carried out under sufficientlyvigorous conditions. However, if desired, isolation of the correspondingperfluorinated unsaturated acids can be accomplished readily bytreatment of the halogenated acids by excess alkali in hot water oralcohol. Since these unsaturated acids are ordinarily oily mixtures ofthe cis and trans stereoisomeric modifications, which are not readilycharacterized or separated, they may be less desirable from thestandpoint of handling in large-scale manufacturing processes.

The perfiuorinated acids of the invention are seen to possess in partthe characteristics of organic carboxylic acids and in part those ofperfluorinated acids. They are, generally speaking, low-melting somewhatwaxy white or slightly colored solids which are substantially insolublein water and hydrocarbon solvents, and are soluble in fluorocarbonsolvents. They further possess the common characteristics of both groupsof acids, namely, that of forming salts with cations of metals such assodium, potassium, calcium, aluminum, zinc, copper, iron, manganese,zirconium and the like and ammonium ion and 'alkyl-substituted ammoniumions such as ethylammonium, piperidinium, dimethylammoniuin,trimethylammonium and tetramethylammonium ions. Depending upon theparticular cation these salts are readily soluble in water as, forexample, the sodium, potassium and ammonium salts; or insoluble, as forexample, the basic aluminum The basic aluminum salt is oleophobic andhydro phobic, but is unexpectedly found to be highly fluophilic, beingsoluble in fluorocarbon solvents.

The acids of the invention can be converted to the corresponding acylhalides, for example to the acyl chloride, by treatment withconventional halogenating agents, such as phosphorus pentachloride andthionyl chloride; and to the acyl fluoride, by treatment of the acylchloride with hydrogen fluoride; and the like. Similarly, by replacementof the chlorine with bromine or iodine, as

by reacting with calcium bromide or calcium iodide, respectively, theacyl chlorides can be converted to the corresponding acyl bromides oracyl iodides. The acids themselves, or especially their anhydrides ortheir acyl halides, can bereacted with alcohols to produce esters,

with ammonia and primary or secondary amines to produce amides andsubstituted amides respectively. Dehydration of the amides yields thecorresponding nitriles.

Treating the acids of the invention and especially derivatives thereofwith hydrazine produces hydrazides, by-

the methods commonly employed for the purpose. Thus it is seen that thecarboxyl group of the acids of the invention is capable of undergoingall of the ordinary reactions of the aliphatic carboxyl group. Theesters can 'also be produced by transesterification of the acids withsuitable esters such as vinyl acetate, this method being particularlyuseful for preparation of esters for which the free alcohol is notstable; or by catalytic esterification, particularly under conditionssuch that water is eliminated from the reaction mixture. Otherconventional reactions of carboxylic acids are also exhibited by 4 inthe copending application of Olson et al., Serial No. 640,569, filedFebruary 18, 1957.

The vinyl and allyl esters of the acids of the invention can behomopolymerized and copolyrnerized inter se as well as with othermonomers and low polymers to form polymeric materials comprisingrecurring units having the formula CHrCHz wherein R and R, have thesignificance set forth hereinabove and n is 0 or 1. These homopolymersand co polymers are suitable for rendering paper and textilesoil-resistant and water repellent.

The following illustrative examples will more specifically describe thecompounds of theinvention and the processes for their preparation.

Example '1 C. Analysis.Found, 28.3% C, 57.7% F, 6.47%

Cl (not significantly changed by recrystallization); calculated, 28.1%C, 58.2% F, 6.39% Cl. 7

The 4-chloro-5-(perfiuorooctyl)-pentanoic acid thus prepared ishydrogenated by shaking a solution of 8.00 g. (0.0145 mole) of the acidand 2.5 g. (0.062 mole) of sodium hydroxide in a mixture of 30 ml. ofwater and 30 ml. ethanol for 3 hours at 140C. in a rocking highpressurehydrogenation apparatus, in the presence of 4 g. of Raney nickelcatalyst and with hydrogen supplied at 2500 p.s.i. pressure. Afterremoval of the catalyst and evaporation to dryness, an amorphous residueis obtained comprising sodium S-(perfiuorooctyl)-pentanoate. -Bydissolving this residue in Water followed by acidification of theresulting solution, the saturated perfluoroalkyl aliphatic acid formedby hydrogenation is recovered as a waxy white solid, which can bedistilled at C. at 0.02 mm. pressure. After recrystallization fromcarbon bisulfide, the 5-(perfluorooctyl)-pentanoic acid thus preparedmelts at about 86.587.3 C.

'Amzlysis.Found 30.0% C, 61.9% F; calculated, 30.0%

, By repeating the foregoing procedure, employingperfiuoro-n-pentanesulfonyl chloride and perfluorododecane- "tively,S-(perfluoropentyl)-pentanoic acid and S-(perfluorododecyl)-pentanoicacid.

Likewise, when S-butenoic acid, 6-heptenoic acid and 13-tridecenoic acidare employed instead of 5-pentenoic acid in carrying out the procedureof this example, there are obtained, respectively, the corresponding4-(pe1fluorooctyl) -butyric acid, 7-(perfluorooctyl)-heptanoic acid and13-(periiuorooctyl)-tridecanoic acid.

Example II An' electrically heated rocking autoclave of 187 ml.

capacity is charged with 37.5 grams of purified 1l--perfiuorooctyl-10-chlorohendecanoic acid (prepared by reaction ofperfluorooctanesulfonyl chloride and 10 'hende'cenoic acid by the methoddescribed in the preced "in'g example), 8.4 grams of potassiumhydroxide, 10 ml.

of water, 60 ml. of absolute ethanol, and 6.0 grams of Raney nickelcatalyst. Hydrogen is introduced at 3000 p.s.i. pressure and theautoclave is rocked for four hours while heating at 150 C. At the end offour hours the autoclave is cooled to about 50 C., flushed with nitrogenand opened. The contents are removed and cautiously filtered hot(avoiding spontaneous ignition of the cat-alyst), and the catalyst iswashed with several 50 ml. portions of hot ethanol. The combinedfiltrate and washings are evaporated to dryness, dissolved in water andacidified with dilute hydrochloric acid, whereupon a waxy precipitateforms and is collected and dried. After distillation at reducedpressure, the ll-(perfluorooctyl)- hendecanoic acid formed in thereaction melts at about 835 to 84.5 C. Analysis.Found, 37.9% C, 53.3% F;calculated, 37.8% C, 53.5% F.

A mixture of 6 g. (0.01 mole) of ll-perfluorooctylhendecanoic acid and100 ml. of 0.1 M alcoholic sodium hydroxide is refluxed untilsubstantially all of the acid has dissolved. The reaction mixture isthen evaporated to dryness on the steam bath or in vacuo. The soapywhite residue is the sodium salt of ll-(perfluorooctyl) -hendecanoicacid.

In the same way, but by use of an equimolar amount of potassiumhydroxide, there is prepared the potassium salt ofll-(perfluorooctyl)-hendecanoic acid.

Likewise, by admixture of an aqueous solution of aluminum chloride andan alcoholic solution containing a slight stoichiometric excess of theacid, a precipitate of the aluminum salt ofll-(perfluorooctyl)-hendecanoic acid is formed. The somewhat sticky,amorphous precipitate is washed with Water and dried. It is soluble inxlyene hexafluoride.

Example III A mixture of 54 g. (.0895 mole) ofll-(perfluorooctyl)-hendecanoic acid and 35 g. (0.28 mole) of thionylchloride is warmed under reflux on a steam bath for about 1 hour,allowed to stand overnight at room temperature, and then heated to thepoint of vigorous refluxing for 2 hours. The resulting reaction mixtureis transferred to a distilling flask and excess thionyl chloride isremoved by distillation. Traces of thionyl chloride still remaining areremoved by heating under reduced pressure and the residual11-(perfluorooctyl)-hendecanoyl chloride is fractionally distilled underreduced pressure, the fraction boiling from 110 to 125 C. at 0.015 mm.of mercury pressure being collected. After redistillation, the1l-(perfluorooctyl)-hendecanoyl chloride thus prepared boils at 125 at0.015 mm. pressure. Analysis. Found, 37.3% C, 5.7% Cl; calculated, 36.7%C, 5.7% Cl.

Example IV Example V Omega-perfluorooctylhendecanoic acid is convertedto a chromium complex by the method described in US. Patent 2,662,835for fully fluorinated acids. The resulting green solid complex materialcannot be structurally characterized by analysis. It is applied tochrome-tanned, split and shaved cowhide sides previously lightlyretanned with vegetable extract in a wet handling drum andconventionally dyed. The chromium complex is applied as follows: Theleather handling drum is drained, and

fresh float water is introduced at 100 F. in amount approximately .equalto the weight of the wet leather, the

pH being adjusted to about pH 3.5-4.0 using formic acid. A 30% alcoholicchromium complex solution having a chromiumzacid mole ratio of 3 :1 isadded in amount sufficient to provide chromium complex equal to 3% ofthe dry weight of the leather. The leather is then drummed until thegreen color of the solution disappears. The treated leather is rinsedfor 2 minutes and set out and dried; and finished in the usual manner.Leather thus prepared has high flexibility and is markedly water andoil-repellent, with good tensile strength.

Example VI Another route for the preparation of the acids of the presentinvention is exemplified by the following procedure:

A solution of 5.0 grams (.00765 mole) of omegaperfluoroootyl-hendecylbromide (prepared by the reduction of omega-perfluorooctyl-hendecanoicacid with lithiurn aluminum hydride to the corresponding alcoholfollowed by treatment with hydrogen bromide) in about 70 ml. of absoluteethanol is mixed with 2 ml. of an aqueous sodium cyanide solutioncontaining 0.008 mole sodium cyanide and refluxed for 72 hours. Thenitrile of omegaperfiuorooctyldodecanoic acid is thus formed. Ifdesired, the omega-perfluorododecanonitrile can be isolated, as byremoval of the solvent by evaporation followed by waterwashing todissolve the soluble constituents of the reaction mixture and drying ofthe Water-insoluble residue, followed by recrystallization from coldether, chloroform or alcohol. However, without isolation from thereaction mixture the omega-perfluorooctyl dodecanonitrile can behydrolyzed to form the corresponding w-perfluorooctyl dodecanoic acid byaddition to the alcoholic reaction mixture of 2.24 grams (0.04 mole) ofpotassium hydroxide dissolved in about 4 ml. of water and refluxing for24 hours. Saponification is not complete under these conditions, andboth the amide and the acid can be isolated from the reaction mixture.The alkaline alcoholic reaction mixture is diluted with water and boiledto expel a portion of the alcohol, acidified by addition of concentratedhydrochloric acid and chilled thoroughly. The precipitate which forms iscollected, washed with water and dried. Extraction with absolute etherfurnishes a soluble fraction and an insoluble fraction.Recrystallization of the ether-soluble fraction from hexane yields 12perfiuorooctyl dodecanoic acid melting at about -82 C. Analysis.Found,38.9% C, 52.2% F; calculated, 38.8% C, 52.2% F. Recrystallization of theetherinsoluble fraction from xylene hexafluoride furnishes 12-perfluorooctyl dodecanoic amide melting at about to 118 C. Analysis.-Found 39.3% C, 2.2% N; calculated, 40.0% C, 2.3% N. The amide isconverted to potassium 12-perfluorooctyl dodecanoate by prolongedrefluxing with aqueous alcoholic potassium hydroxide.

Example VII To a mixture of 65 grams (0.75 mole) of vinyl acetate, 75grams (0.125 mole) of 1l-perfluoroocty1-l0- hendecenoic acid (preparedby refluxing omega-perfluorooctyl-10-chlorohendecanoic acid for 2 hourswith excess alcoholic potassium hydroxide and isolating and distillingthe resultant acid) and 1.5 grams of mercuric acetate is continuouslyadded 0.36 gram of concentrated sulfuric acid. The reaction mixture isallowed to stand at room temperature for about thirteen days to effectester interchange. One gram of sodium acetate is added, the excess vinylacetate is removed by evaporation under reduced pressure, and theresidue is transferred to a distillation flask and fractionallydistilled rapidly'under reduced pressure. The fraction, boiling at 50 toC. at the pressure of 0.4 mm. of mercury is collected and redistilledthrough a Vigreaux column to give vinyl 11-perfluorooctyl-IO-hendecenoate, a colorless liquid boiling at 122-124 atabout 0.015 mm. of mercury pressure, and possessing n =1.3768.Analysis.-Found, 40.3 c, 51.5% F; calculated, 40.3% c, 51.6% F.

'7 Example VIII By employing substantially the same procedure as that'set forth in Example VII, the vinyl ester ofII-(perfluorooctyl)-hendecanoic acid is prepared. In this case, becauseof the lower solubility of the saturated acid, it is necessary to heatthe mixture of 9 grams of acid, 7.75 grams of vinyl acetate and 0.18gram of mercuric acetate to 40 C. until the acid does not precipitatefrom the mixture on cooling to room temperature. The mixture is thenallowed to stand at room temperature for five days and worked up. Thefraction boiling at about 125 to 132 C. at 0.35 mm. of mercury pressureis collected. The vinyl ester of 11perfluorooctyl-hendecanoic acid thusprepared is a soft solid which melts at about 38 C. Analysis-Found,40.4% C, 51.2% F; calculated, 40.1% C, 51.3% F. The amount of mercuricacetate employed in the procedure can be varied slightly withsubstantially the same results.

Example IX Vinyl 1l-perfluorooctyl-10-ch1oro-hendecanoate, prepared byesterification of 1l-perfluorooctyl-10-chlorohendecanoic acid with vinylacetate under conditions of ester interchange as hereinbefore disclosed,can be polymerized either in bulk or in emulsion form. A mixture of 1.0gram of vinyl 11-perfiuorooetyl-10-chlorohendecanoate and 0.01 g. of 25%solution of acetyl peroxide in dimethyl phthalate is heated under vacuumin a sealed ampoule at 50 C. for 42 hours. A rather hard, opaque, waxypolymer is formed which is insoluble in acetone. It is dissolved inxylene hexafluoride and precipitated with methanol, collected and driedin vacuurn at 50 C.

Emulsion polymerization of vinyl ll-perfiuorooctyl- 10chloro-hendecanoate is effected using 1.0 g. monomer, 1.8 g. water, 0.05g. of the potassium salt of 11- (perfluorooctyl)10-hendecanoic acid and0.0030 g. potassium persulfate in an ampoule which is frozen, evacuatedand thawed for two cycles before heating at 50 C. for 42 hours. Theresulting latex contains 10% polymer solids, with inherent viscosity in2:1 methyl perfluorobutyrate-acetone of about 0.32.

Example X Vinyl 11perfluorooctyl-hendecanoate is emulsionhomopolymerized by heating a mixture of 0.25 gram of the monomer, 0.46g. of 2.8% aqueous dodecylamine hydrochloride solution and 0.0013 g.potassium persulfate. The resulting latex contains 14.8% solids,indicating 38% conversion. The intrinsic visocity in 2:1 methylperfiuoro-butyrate-acetone is 0.32.

Better conversion is obtained when highly fluorinated emulsifying agentsare used in place of the dodecylamine hydrochloride and when a portionof the water is replaced by a solvent such as trifluoroethanol oracetone. When the procedure is repeated using the same proportionsexcept that the emulsifier is a 2.8% solution of potassium1l-perfluorooctyl-hendecanoate in water and 0.113 g. of the water isreplaced by that weight of trifluoroethanol, there is obtained afterabout 118 hours at about 52 C. a milky latex with slight bluish colorand no precoagulum, containing 30.4% washed solids corresponding to 86%conversion, with intrinsic viscosity in 2:1 methylperfiuorobutyrate-acetone of 0.11.

Similarly, using a 2.8% aqueous solution of potassium(N-ethylperfluorooctanesulfonamido)acetate as emulsifier and 0.135 g. ofacetone in place of the same weight of water, a cloudy, blue latex withno precoagulum is obtained in about 118 hours at 52 C. The latexcontains 28.7% solids, corresponding to 78% conversion; intrinsic'viscosity in 2:1 methyl perfluorobutyrate-acetone =0.20. It is thus seenthat the potassium salt of an acid of this invention possesses utilityas an emulsifying agent while at the same time the vinyl ester is apolymerizable monomer. i

whereinR; represents a monovalent, functionally-unsub- A copolymer isprepared from 20 g. of the above vinyl 11perfluorooctyl-hendecanoate and1.47 g. of maleic anhydride (2:1 molar ratio) made up as 50% solution intoluene, to which 1% benzoyl peroxide is added. The mixture is refluxed14 hours, a further 1% of benzoyl peroxide is added and after heatingfor 7 hours longer the solution is diluted to 35% solids with methylethyl ketone and precipitated with methanol, giving a polymer softeningabove 60 C. When applied to paper or cloth as a 5% solution in methylethyl ketone, and the solvent permitted to evaporate, the paper or clothis rendered oil and water-repellent.

Example XI Allyl esters are prepared by azeotropic removal of water withbenzene or toluene from a mixture of the terminally perfluoroalkylaliphatic acid and allyl alcohol using a sulfonic acid catalyst for theesterification. Esters are thus prepared from 6.0 g. (0.01 mole) of 11-perfluorooctyl-hendecanoic acid with 5.8 g. (0.10 mole) of allyl alcoholand from 16 g. (0.025 mole) of 11-perfiuorooctyl-10-ch1oro-hendecanoicacid with 10 g. of allyl alcohol, to produce, respectively, allylll-perfiuorooctyl-hendecanoate and allyl1l-perfluorooctyl-10-chlorohendecanoate. The esters are purified bydistillation under reduced pressure.

Example XII Following the procedure of Example I above, a mixture of28.8 g. of perfluoro-(4-ethylcyclol1exane)sulfonyl chloride, 9.2 g. ofIO-hendecenoic acid and 1.0 g. of di t-butyl peroxide is heated to 145C. under reflux and held at that temperature for two hours. The reactionproduct is subjected to high vacuum distillation in a short pathdistilling apparatus. The fraction boiling at C. at 0.01-0.04 mm. iscollected. A pasty brown solid is recovered, and is redistilled at 130C. and 0.010 mm., to produce a mushy semi-solid comprising10-chloro-ll-perfiuorm(4-ethylcyclohexyl)hendecanoic acid.

This product is probably a mixture of stereoisomeric materials, owing tothe nature of the perfluoro-4-ethylcyclohexyl group. Analysis.Found,5.9% Cl; calculated for 4 C F5C F1 -H CHCI(CH 3-CO2H 6.0% Cl. 7

By combination of a fractional melting procedure with recrystallizationa solid acid is isolated which is considered to have the transconfiguration. The crude acid is placed in a heavy-walled centrifugetube fitted with a sealed-in porous porcelain plate so that uponcentrifugation liquid material is readily separated from solid.centrifuging is started at 25 C. and allowed to proceed until the tubeand contents have been warmed to about 39 C. The solidIO-chloro-l1-(perfluoro-4-ethylcyclohexyl) hendecanoic acid thusobtained melts at 460 to 480 C. Analysis.-Found, 37.9% C., 46.1% F, 6.2%Calculated for C19H20F1502Cl, C, F, 5.9% Cl.

A solution of 14.0 g. (0.023 mole) of the chlorinated acid of meltingpoint 4648 C. and 4.0 g.(0.1 mole) of sodium hydroxide in a mixture of40 rnl. each of ethanol and water is hydrogenated under 2500 psipressure of hydrogen with Raney nickel catalyst for 3 hours at C.,followed by 3 hours at 180 C. in a rocking autoclave as in previousexamples. The workup furnishes an ambercolored oily acid which isrecrystallized from methylene chloride at 25 C. to give the desiredll-(perfluoro-4- ethylcyclohexyl)hendecanoic acid melting at 55-60 C.Analysis.-Found, 41.4% C, 48.6% F; calculated, 40.3% C, 50.8% F.

What is claimed is:

1. A compound of the group consisting of terminallyperfluoroalkyl-substituted aliphatic carboxylic acids represented by theformula:

stituted perfluorinated group having from 4 to 12 carbon atoms and R isa straight chain alkylene group having from 1 to 12 carbon atoms, andthe carboxyl-linked derivatives thereof selected from the classconsisting of cationic salts, cationic complexes, acyl halides,anhydrides, amides, amidines, nitriles, hydrazides, peroxides, estersand orthoesters.

2. A compound of the group consisting of -(perfluorooctyl)-pentanoicacid, and the carboxyl-linked derivatives thereof selected from theclass consisting of salts, cationic complexes, acyl halides, anhydrides,amides, amidines, nitriles, hydrazides, peroxides, esters andorthoesters.

3. A compound of the group consisting of ll-(perfluorooctyl)-hendecanoicacid and the carboxyl-linked derivatives thereof selected from the classconsisting of cationic salts, cationic complexes, acyl halides,anhydrides, amides, amidines, nitriles, hydrazides, peroxides, estersand orthoesters.

4. A compound of the group consisting ofll-(perfluoro-4-ethyl-cyclohexyl)hendecanoic acid and thecarboxyl-linked derivatives thereof selected from the class consistingof cationic salts, cationic complexes, acyl halides, anhydrides, amides,amidines, nitriles, hydrazides, peroxides, esters and orthoesters.

5. A compound of the group consisting of 12(perfluorooctyl)dodecanoicacid and the carboxyl-linked derivatives thereof selected from the classconsisting of cationic salts, cationic complexes, acyl halides,anhydrides, amides, amidines, nitriles, hydrazides, peroxides, estersand orthoesters.

6. l2-(perfluorooctyl)dodecanoic amide.

7. ll-(perfiuorooctyl)hendecanoyl chloride. I

8. Vinyl 1l-(perfiuorooetyl)hendecanoate.

9. Sodium S-(perfluorooctyl)pentanoate.

10. Potassium ll-(periluorooctyl)-hendecanoate.

11. ll-(perfluorooctyl) -hendecanoic amide.

12. Aluminum 1l-(perfluorooctyl)hendecanoate.

13. A polymer of a compound of the formula:

wherein R represents a monovalent, functionally-unsubstitutedperfluorinated group having 4 to 12 carbon atoms, R is a straight chainalkylene group having 1 to 12 carbon atoms, and n is a number of thegroup consisting of 0 and 1.

14. A process for the production of terminally perfluoroalkylatedaliphatic carboxylic acids which comprises subjecting a halogenated acidrepresented by the formula:

wherein R represents a monovalent, functionally unsubstitutedperfluorinated group having from 4 to 12 carbon atoms and RX representsa straight-chain alkylene group having from 1 to 12 carbon atoms andhaving a halogen other than fluorine attached to the carbon atom thereofwhich is adjacent to the methylene group connected to the saidperfluorinated group, to the action of hydrogen under pressure in thepresence of a hydrogenation catalyst. 15. A polymer of a compound of theformula:

wherein R; represents a monovalent functionally-unsubstitutedperfluorinated group having 4 to 12 carbon atoms, R is a straight chainalkylene group having 1 to 12 carbon atoms, and n is a number of thegroup consisting of 0 and l. i

19. 5- (perfluorooctyl)pentanoic acid.

20. ll-(perfiuorooctyl)hendecanoic acid.

21. 11-(perfiuoro-4-ethyl-cyclohexyl) -hendecanoic acid.

22. lZ-(perfluorooctyl)dodecanoic acid.

23. Terminally perfiuoroalkyl-substituted aliphatic carboxylic acids ofthe formula:

R CH R-CH COOH wherein R represents a monovalent,functionally-unsubstituted perfluororinated radical having from 4 to 12carbon atoms and R is a straight chain alkylene group having from 1 to12 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS2,240,275 Whitmore et al. Apr. 29,1941 2,322,258 Strosacker et al June22, 1943 2,367,078 Weizmann I an. 9, 1945 2,592,069

Reid Apr. 8, 1952 UNITED STATES PATENT OFFICE CERTIFICATION OFCORRECTION Patent No. 2,951,051 August 30, 1960 George V, Do Tiers It ishereby certified that error appears in the above numbered patentrequiring correction and that the said-Letters Patent should read ascorrected below.

Column 5 line 33, for "Xlyene" read xylene column 7, line 36 for "10chloro-" read lO-chloro- H H column 8, line 43 for 4 C F C F read 4 C FC FL I column 10, line 24, the formula should appear asshown belowinstead of as in the patent:

Rf-CH2RCH2COO(CH2) CH=CH2 Signed and sealed this 6th day of June 1961,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of PatentsUNITED STATES PATENT OFFICE CERTIFICATION OF CORECTIQN Patent No.2,951,051 August 30 1960 George V., D, liers It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected belowo Column 4, lines7 to 13, the formula should appear as shown below instead of as in thepatents CH-CH column 9, line 38, beginning with 13 A polymer of acompound" strike out all to and including "0 and 10-", in line 45, samecolumn 9; in the heading the printed specification line 8 for "23Claims, read 22 Claims,

Signed and sealed this 31st day of October 1961.,

(SEAL) Attest:

ERNEST w. SWIDER AVID L LADD Attesting Officer Commissioner of Patents

1. A COMPOUND OF THE GROUP CONSISTING OF TERMINALLYPERFLUOROALKYL-SUBSTITUTED ALIPHATIC CARBOXYLIC ACIDS REPRESENTED BY THEFORMULA: